Desulphurizing hydrocarbon oils



Patented Dec. 12, 1933 UNITED STATES 1,938,671 DESULPI'IURIZHING HYDROOARBON OILS Frederick W. Sullivan, .Jr., and Arthur,B.-Brown, Hammond, Ind., assignors to Standard Oil Company, Whiting, Ind, a corporation of Indiana No Drawing. Application July 5, 1929 Serial No. 376,277

4 Claims.

The present invention relates to improvements in desulphurizing hydrocarbon oils, and more particularly the lower boiling point distillates such as distillates in the gasoline and kerosene boiling point range. It has been found particularly suited for use in connection with cracked distillates from high sulphur oil, such as Lander and Winkler oils which distillates contain sulphur bodies of a highly refractory type and which are diflicult to remove.

In accordance with the present invention, the alkali metals such as sodium and potassium are preferably employed to effect the desulphurizing. The metal may be employed preferably in dispersed form; for example, in such a high degree of dispersion as is secured by the use of the colloid mill.

In carrying out the invention, the active metal is employed in a proportion equal to or substantially exceeding the atomic equivalent of the amount of sulphur present. In general, the atomic ratio of the metal to the sulphur should exceed 1 to 1 and proportions in excess of 3 to 1 are preferred. The distillate and the active metal are heated together to a temperature of at least 350 F., and preferably not exceeding 650 F. The operation is conducted under pressure, with low boiling distillates generally in excess of 150 lbs. per sq. in. and preferably from 200 to 300 lbs. per sq. in. Higher pressures are employed when lower boiling constituents are present.

As an example of the operation, a gasoline derived by a vapor phase cracking operation from a high sulphur crude oil was treated with sodium, the atomic ratio of sodium to sulphur being 4 to 1 at a temperature of 575 F. and a pressure of 290 lbs. per sq. in. for three hours, the percentage of sulphur being reduced from an initial value of 0.182 to 0.087. The same gasoline treated with a higher proportion of sodium, the atomic ratio of sodium to sulphur being 6.3, at 575 F. under 300 lbs. per sq. in. pressure, the sulphur was reduced to 0.016%.

In carrying out the operation to desulphurize oils in the gasoline boiling point range, it has been found desirable to separate the lower boiling portions of the distillate; that is, the portions coming over below 200 F. to 325 F. and which is ordinarily satisfactorily low in sulphur content, and to treat only the cut remaining. In treating the heavier cut produced in this Way, it has been found that a lower proportion of the active metal is required and lower pressures may be employed than when the entire gasoline is treated. Thus, with the same gasoline as that employed in the illustrative example above, the gasoline was cut by distillation into two fractions at 225 F. The lower boiling fraction, from the initial boiling point to 225 F, had a sulphur content without treatment of 0.058%. The higher boiling cut from 225 F. to 420 F. was adequately desulphurized with sodium in an atomic ratio relative to the sulphur of 3.25 at a temperature of 550 F. and a pressure of about 250 lbs. per sq. in. The point at which the cut is made between the lighter and heavier fractions obviously varies with different oils in accordance with the distribution of the sulphur; thus, with some oils it has been found satisfactory to make the out at 325 F. The proper point may be readily determined by determining the sulphur distribution in the different cuts of the oil experimentally, and thus determining the proper temperature at which a maximum lower boiling fraction has a satisfactorily low sulphur content.

To further illustr'ate the invention, the 225 F. to 420 F. cut of another distillate derived by an ordinary cracking process from a sulphurcontaining crude was treated with sodium in an atomic ratio relative to the sulphur of 4 to 1 at a temperature of 550 F. and a pressure of 240 lbs. per sq. in, the sulphur content being reduced from 0.339% to 0.207%. The same cut treated with sodium in the atomic ratio of 6'to 1 at a temperature of 575 .F. and a pressure of 280 lbs. per sq. in. had its sulphur content reduced to 0.039%.

Other alkali metals, such as lithium, potassium and the like are similarly efiective. Thus a 225 F. to 420 F. cut of a sulphur-containing pressure distillate, on treatment with potassium in the atomic ratio of 4.2 to 1 at 575 F. and 250 lbs. per sq. in. pressure for three hours had its sulphur content reduced from 0.781% to 0.014%. A 325 F. to 420 F. cut, of another distillate, treated with potassium in the atomic ratio of 5.5 to 1 at a temperature of about 630 F. and a pressure of about 250 lbs. per sq. in. for three hours had its sulphur content reduced from 1.105% to 0.021%.

We claim:

1. In a process of desulphurizing a pressure 105 distillate having an objectionably high sulphur content, the sulphur content of successively higher boilingfractions of said distillate increasing in general with the boiling point, the steps which consist in :Eractionally redistilling said dis- 110 tillate, discontinuing theredistillation when the temperature has risen to a point approximately within the range 200 F. to 325 F., coagitating the bottoms from said redistillation with an alkali metal at a temperature of from 350 F. to 650 F. under a pressure in excess of 150 lbs. per sq. in. to reduce its sulphur content to an unobjectionable point and reblending the treated bottoms with the overhead from said redistillation.

2. In a process of desulphurizing a pressure distillate having an objectionably high sulphur content, the sulphur content of successively higher boiling fractions of said distillate increasing in general with the boiling point, the steps which consist in fractionally redistilling said distillate, discontinuing the redistillation when the the temperature has risen to a point approximately within the range 200 F. to 325 F., coagitating the bottoms from said redistillation with metallic sodium at a temperature of from about 350 F. to about 650 F. under a pressure in excess of about 150 lbs. per sq. in. to reduce its sulphur content to an unobjectionable point and reblending the treated bottoms with the overhead from said redistillation.

3. Process steps according to claim 1 in which said alkali metal is used in a quantity of at least three atoms for every atom of sulphur in said bottoms.

4. Process steps according to claim 2 in which said alkali metal is used in a quantity of at least three atoms for every atom of sulphur in said bottoms.

FREDERICK W. SULLIVAN, JR. ARTHUR B. BROWN. 

